Voltage stabilizer including light coupling between gas discharge tube and photoresistor



Aug. 16, 1966 J. DEELMAN G. 3,267,354 VOLTAGE STABILIZER INCLUDING LIGHT COUPLING BE GAS DISCHARGE TUBE AND PHOTORESISTOR Filed Sept. 18, 1962 TWEEN 2 1'. is a 10mA INVENTOR GERARDLB J. LEELMAN Y Y Q $22K? United States Patent 3,267,354 VOLTAGE STABILIZER INCLUDING LIGHT COU- PLING BETWEEN GAS DISCHARGE TUBE AND PHOTORESISTOR Gerardus Jacobus Deelman, Emmasingel, Eindhoven,

Netherlands, assignor to North American Philips Company, Inc., New York, N.Y., a corporation of Delaware Filed Sept. 18, 1962, Ser. No. 224,404 Claims priority, application Netherlands, Sept. 21, 1961, 269,485 2 Claims. (Cl. 32321) The invention relates to voltage stabilization circuits using a gas-discharge tube. In particular, it relates to such circuits in which a photosensitive resistor is used in combination with a gas-discharge tube.

It is common knowledge to use gas discharge tubes in order to obtain a stabilized voltage, since the operating voltage of suitably chosen gas-discharge tubes, for example neon tubes, is substantially independent of the current I through the tube. Experiments have shown, however, that the operating voltage V is only approximately constant. Even carefully built tubes will exhibit a differential resistance dV/dl which is not negligible.

The primary object of the invention is to provide voltage stabilization circuits using gas-discharge tubes in which more precise stabilization can be achieved. According to the invention, a photosensitive resistor is connected in parallel or in series with the circuit comp-rising the gas-discharge tube. With the parallel connection, a stabilized voltage is set up across the photosensitive resistor; with the series connection, a stabilized voltage is set up across the series combination of the gas-discharge tube and the photosensitive resistor.

The invention is based on the recognition that the quantity of light emitted in a gas-dis-charge tube by the ionized gas increases with the current through the tube in particular, this increase is substantially linear with a suitably chosen construction and gas filling. This variation of the emitted quantity of light with the currrent is utilized by causing the light to strike a photosensitive resistor connected in parallel or in series with the circuit including the gas-discharge tube. As is known, a photosensitive resistor, for example a cadmium-sulphide resistor, has the property that its resistance value varies with the quantity of light striking it, the resistance decreasing with an increase in the quantity of light and increasing with a decrease in the quantity of light.

When a gas-discharge tube and .a photosensitive resistor are connected in parallel, the total current is divided between the two components of the parallel combination so that the voltage across the parallel combination remains substantially constant. This parallel combination may advantageously be used with voltage control of the stabilizing element. be understood to mean that the internal resistance of the relevant source of supply is low With respect to its load resistance.

In a series combination of the gas-discharge tube and the photosensitive resistor, the voltage across the gasdischarge tube will not be constant, but the voltage across the series combination and across the photosensitive resistor respectively is substantially constant. This series combination may advantageously be used with current control of the stabilizing element. The term current control is to be understood to mean that the internal resistance of the relevant source of supply is high with respect to its load resistance.

The objects and features of the invention will be better understood from the following description thereof, taken in conjunction with the drawin in which:

FIG. 1 is a schematic circuit diagram of the voltage stabilizer in accordance with the invention in which there The term voltage control is to z Ice is provided a parallel combination of a gas-discharge tube and a photosensitive resistor;

FIG. 2 is a graphical representation of the voltage variation across the gas-discharge tube without a photo'- sensi-tive resistor. FIG. 2 also shows the voltage variation across the parallel combination of a gas-discharge tube and a photosensitive resistor;

FIG. 3 shows another embodiment of a voltage stabilizer in accordance with the invention using the parallel combination and a transistor; and

FIG. 4 shows a schematic circuit diagram of a voltage stabilizer in accordance with the invention in which there is provided a series combination of a gas discharge tube and a photosensitive resistor.

In the diagram of FIG. 1, a variable voltage U, which may be an incompletely rectified alternating voltage or a D.C. voltage containing a ripple, is connected between terminals 1 and 2. This voltage is supplied through a resistor 5 to the parallel combination of a neon tube 3, for example of the type A2, and a photoresistor 4, which may be composed of cadmium sulphide. The voltage V across this combination has been found to be substantially constant over a wide current range. This is best shown in FIG. 2, wherein curve 10 shows the measured deviation AV of the operating voltage of the neon tube 3 at a current I with respect to the operating voltage at a very small current. Curve 20 shows the measured deviation AV across the parallel combination of the neon tube 3- and the cadmium sulphide resistor 4 as a function of the total current I through this parallel combination. As can be seen from a comparison of the curves of FIG. 2, the parallel combination provides much improved stabilization.

If required, a resistor 18 may be connected in series with the gas-discharge-tube 3, in order to prevent too large a current flow through the tube as a result of the difference between the voltage U and the operating voltage of the tube.

In the diagram of FIG. 3, the parallel combination of the neon tube 3 of the so-called Stabilovolt type and the photoresistor 4 is connected to the base of a transistor 6 having a high dissipation; the transistor may be, for example, of the type ASZ 16. The parallel combination is common both to the external collector-base circuit and to the external emitter-base circuit of the transistor. In addition to the variable input voltage U a variable reference voltage U is applied through resistor 8 to the base of transistor 6. In a practical embodiment, the variable direct voltage U was 300 v., and the variable reference voltage U was 320 v. The value of the resistor 8 was approximately 4,0009. The voltage across the parallel combination 3, 4 was again substantially constant (approximately 260 v.) and consequently (as a result oi the transistor properties) the voltage across the load 7 in the emitter circuit is also substantially constant.

In the circuit diagram of FIG. 4, the variable current source 15 passes a current I through the series-combination of a gas-discharge tube 3 and a photosensitive resistor 4. A stabilized voltage V can be taken from the series-combination or a stabilized voltage V, can be taken from the resistor 4; the latter is possible since the quantity of light produced by the tube 3- increases with increase of the current I (and consequently of the voltage drop across the tube 3) and the resistance normally decreases with increased current. Consequently, the value of the resistor 4 decreases when irradiated by light from the tube 3- and with suitable proportioning it may be achieved that either the product of the resistance value of resistor 4 and the current I is constant or that this product decreases to such an extent that the increasing voltage drop at the tube 3 is compensated for.

Many modifi caltions of the embodiments described above will be apparent to those skilled in the art Without departing from the inventive concept, the scope of which is delimited in the appended claims. It is also noted that the quantitative values given are for illustrative purposes only and to enable ready practice of the invent-ion.

What is claimed is:

1. A voltage stabilizing circuit arrangement comprising: input terminals adapted to be connect-ed to a source of variable voltage, a transistor having emitter, base and collector electrodes, one of said terminals being connected to said collector electrode, a gas discharge tube connected between said base electrode and the other of said input terminals, a photosensitive resistor connected in parallel with said tube, a source of reference voltage coupled to said base electrode, said resistor and said tube being arranged such that the light from said tube impinges on said resist-or, the change in resistance of said resistor due to the impingement of light thereon compensating for changes in voltage across the tube, and a load circuit coupled to said emitter electrode for deriving a stabilized voltage therefrom.

2. A voltage stabilizing circuit arrangement comprising; input terminals adapted to be connected to a source of variable current, a gas discharge tube and a photosensitive resistor connected in series combination coupled References Cited by the Examiner UNITED STATES PATENTS 3,062,961 11/1962 Kalns et al 250206 3,078,410 2/1963 Thomas 32322 3,210,549 10/ 1965 Van Santen et al. 250213 OTHER REFERENCES Haining, L. E.: Triggerable Flip Flop Circuit With Electroluminescent and Photoconductive Elements, in RCA Technical Notes, No. 390, June 1960.

JOHN F. COUCH, Primary Examiner.

LLOYD McOOLLUM, Examiner.

D. L. RAE, H. B. KATZ, K. D. MOORE,

Assistant Examiners. 

1. A VOLTAGE STABILIZING CIRCUIT ARRANGEMENT COMPRISING: INPUT TERMINALS ADAPTED TO BE CONNECTED TO A SOURCE OF VARIABLE VOLTAGE, A TRANSISTOR HAVING EMITTER, BASE AND COLLECTOR ELECTRODES, ONE OF SAID TERMINALS BEING CONNECTED TO SAID COLLECTOR ELECTRODE, A GAS DISCHARGE TUBE CONNECTED BETWEEN SAID BASE ELECTRODE AND THE OTHER OF SAID INPUT TERMINALS, A PHOTOSENSITIVE RESISTOR CONNECTED IN PARALLEL WITH SAID TUBE, A SOURCE OF REFERENCE VOLTAGE COUPLED TO SAID BASE ELECTRODE, SAID RESISTOR AND SAID TUBE BEING ARRANGED SUCH THAT THE LIGHT FROM SAID TUBE IMPINGES ON SAID RESISTOR, THE CHANGE IN RESISTANCE OF SAID RESISTOR DUE TO THE IMPINGEMENT OF LIGHT THEREON COMPENSATING FOR CHANGES IN VOLTAGE ACROSS THE TUBE, AND A LOAD CIRCUIT COUPLED TO SAID EMITTER ELECTRODE FOR DERIVING A STABILIZED VOLTAGE THEREFROM. 